AUTOINVOICE FAIL DUE TO TAX ROUNDING

[kittuanem]

Hi Below are the Issue Details
Sales Order created for 2 qty with Price of $ 8521 totaling $17042 with a discount modifier of 25% on it so order value is $12781.50 with a tax of 5%.Invoice is created for the above Sales order and the details are as below.
Invoice Line - $ 12781.50 and Tax - $ 639.07 Totaling -$ 13420.57 .

But the customer is eligible for 100% Discount
so the discount modifier is changed to the 100%.

Retrobilling is used for giving credit for the discount difference.
System generated a Retrobill order for the difference in the Discount amounting $ -12781.50.

When trying to create the Credit memo Autoinvoice is failing with the following message.
"Errors: 1) The total amount of your credit memo cannot exceed the balance of the debit item it is crediting"

The issue is due to tax rounding calculation i.e tax on the 12781.50 is 639.075 which is getting rounded to 639.08 because the tax ronding option is "Nearest".

Is there a way to avoid these ronding errors?

Thanks
Sai